Multi-elastomer seal

ABSTRACT

A system, in certain embodiments has, a fluid seal having a seal body, including a seal interface having one or more engagement portions, a first elastomer portion disposed along the seal interface, and a second elastomer portion disposed along the seal interface, wherein the first and second elastomers have material properties that are different from one another.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/972,049, entitled “Multi-Elastomer Seal”, filed on Sep. 13, 2007,which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to seals within a fluid system. Moreparticularly, the present invention relates to an elastomeric sealsuitable for use in the harsh environment, temperatures, and pressuresof mineral extraction systems, for example.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Fluid systems, such as mineral extraction systems (e.g. oil and gas) andtransport systems, typically include multiple segments of tubing,valves, and connectors that are sealed together by various seals. Theseseals are often subjected to harsh environmental conditions, such ascorrosive fluids, extreme pressures, and extreme temperatures. Moreover,seals are often disposed in remote equipment, such as a marine (e.g.,subsea) wellhead, which can make access and repair difficult andexpensive. In mineral extraction applications, seals are typicallyconstructed of a metal or an elastomer. Metal seals provide long-termresistance to well bore fluids, temperatures and pressures, but oftenrely on high installation forces and complicated design and geometry toprovide reliable sealing. Elastomeric seals typically have a simpledesign that can be installed with low installation forces. Further,elastomeric seals may provide a seal across imperfections (e.g., damage,concentricity and ovalities) on sealing surfaces, and have largermanufacturing tolerances, concentricity and ovalities allowances.Elastomeric seals are generally formed from a single elastomer that isdesigned for use in a particular environment. For example, anelectrometric seal including specific material may be employed based onthe seal's anticipated operating temperature, pressure and chemicalexposure. Accordingly, the electrometric seal is often limited to use ina given range of pressures, temperatures, surrounding chemicals.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a block diagram of a multi-elastomer seal disposed in a fluidsystem, in accordance with embodiments of the present technique;

FIG. 2 is a partial cross-section of an exemplary embodiment of themulti-elastomer seal of FIG. 1;

FIG. 3 is a plot of stiffness versus temperature for two elastomers usedto form the multi-elastomer seal; and

FIGS. 4-23 are partial cross-sections of alternate exemplary embodimentsof the multi-elastomer annular seal of FIG. 1.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Moreover, the use of “top,” “bottom,” “above,” “below,” and variationsof these terms is made for convenience, but does not require anyparticular orientation of the components.

FIG. 1 is a partial cross-sectional view of an embodiment of a fluidsystem 10 having one or more seals 12 between an inner body 14 and anouter body 16. In certain embodiments, the fluid system 10 includes amineral extraction system for the extraction of subterranean naturalresources, such as oil and gas. For example, in the illustratedembodiment, the outer body 16 includes a wellhead 18 coupled to amineral deposit 20 via a well 22. The inner body 14 includes a hanger 24disposed in a wellhead bore 26 and supported by the wellhead 18, forexample. It will be appreciated that in the case of mineral extractionsystems, the inner and outer bodies 14 and 16 may include any number ofcomponents, such as christmas trees, casing hangers, casing heads,casing strings, tubing hangers, tubing heads, tubing strings, runningtools, blowout preventers, valves, flanges, and the like. In mineralextraction and similar systems, the seal 12 may be used with workingpressures including 20,000 pounds per square inch (psi). In other words,in certain embodiments, the seal 12 may be used to isolate regions ofgasses or fluids with pressure differentials across the seal 12 of15,000 psi or greater. Further, the operating environment of suchsystems may include temperatures ranging from −50° F. to 350° F.

As discussed in further detail below, embodiments of the seal 12generally include a plurality of elastomers. For example, the seal 12may include different portions made of different elastomers havingdifferent characteristics, such as stiffness, chemical resistance,behavior as a function of temperature, and so forth. In someembodiments, the plurality of elastomers may be formed into a singlebody. The illustrated seal 12 includes a combination of an outerelastomer and an inner elastomer formed into a homogeneous body (e.g.,single common/solid body). In certain embodiments, the outer elastomerincludes a hard material, and the internal elastomer includes arelatively soft material, or vice-versa. The hard outer elastomerpossesses properties that are conducive to sealing in high-pressure andhigh-temperature environments, and the inner elastomer possessesproperties that are conducive to sealing in high-pressure andlow-temperature environments. Accordingly, in certain embodiments, theouter elastomer is used for sealing, protecting, and isolating the innerelastomer from high-pressure media in high-temperature environments, andthe inner elastomer is used for sealing at high temperatures and/or whenthe environmental temperatures are below effective sealing temperaturesof the outer elastomer. In other words, the seal 12 includes a firstmaterial or property that is effective to seal mutually exclusivelywithout the second material or property in certain conditions, while thesecond material or property is effective to seal mutually exclusivelywithout the first material or property in other conditions. Thus, theembodiments of the seal 12 described in detail below are particularlywell suited for use in a wide range of temperatures (e.g., high and lowtemperatures) and chemical environments.

FIG. 2 illustrates a cross-sectional view of an exemplary embodiment ofthe seal 12. The illustrated embodiment includes the annular seal 12having a body 50, a first elastomer portion 52, a second elastomerportion 54, an inner face 56, an outer face 58, a top face 60, a bottomface 62, and a longitudinal axis 64. As will be appreciated, the body 50of the annular (e.g., radial) seal 12 includes a ring-like membercentered about the longitudinal axis 64. The inner face 56 includes theinnermost diameter of the body 50 that generally interfaces with (e.g.,contacts) the inner body 14. The outer face 58 includes the face of theseal 12 on the outermost diameter of the body 50 that generallyinterfaces with (e.g., contacts) the outer body 16. Accordingly, theinner face 56 and the outer face 58 provide a fluid seal between theannular seal 12 and the inner body 14 and the outer body 16,respectively.

In an annular seal configuration, the seal 12 is generally set by aradial load that compresses or expands the seal into contact withcomplementary sealing surfaces (e.g., inner and outer bodies 14 and 16).For example, the inner body 14 may include a section with a smallerdiameter, a section with a larger diameter, and a tapered sectionbetween the two sections. Thus, urging the seal 12 onto the inner body14 and over the tapered section from the small diameter section to thelarge diameter section provides an axial loading that biases the seal 12outward and compresses the seal 12 against the outer body 16. Similarly,a taper on the outer body 16 may provide a compressive load on a seal 12to generate an inward radial loading that compresses the seal 12 againstthe inner body 14. In general, the top face 60 and the bottom face 62generally do not seal with a complementary surface. However, in a packerarrangement, the top face 60 and the bottom face 62 may generally beused as locations to apply loads to seat, set, and/or lock the seal 12in place. In other words, the top and bottom faces 60 and 62 mayexperience axial loads to push the seal 12 into position, to compressthe seal 12 such that it expands radially between the inner body 14 andthe outer body 16, and to hold the seal 12 in place. For example, a toolmay be forced against the top face 60 until the bottom face 62 contactsa surface and/or another tool, and to load the top face 60 in adirection parallel to the longitudinal axis 64 to compress the seal 12,causing the seal 12 to expand radially. The radial expansion may causethe outer and inner faces 56 and 58 to bias against the outer body 16and the inner body 14, creating a fluid seal between the respectiveinterfaces. Continuing to apply the axial force (e.g., locking the seal12) may maintain the radial expansion and, thus, maintain the fluidseal.

The portion of the seal 12 (e.g., the seal interface) that engages thecomplementary surfaces (e.g., the inner body 14 and the outer body 16)may be may include a variety of shapes and configurations. For example,the seal interface may include a continuous surface that is formed fromone or more materials. In an embodiment wherein the complementarysealing surface generally conforms to the contour of the seal 12 (e.g.,a relatively flat surface), the sealing interface may include a singleengagement portion that extends across a surface of the seal 12. In anembodiment where the complementary surface includes a surface that doesnot conform to a surface of the seal 12 (e.g., an interrupted surface),the seal interface may include one or more engagement portions at eachlocation where the seal 12 contacts the complementary surface. Further,the seal 12 may include a plurality of interruptions along its sealingsurface. For example, the seal 12 may include one ore more bumps,protrusions, indentations, recesses, or similar features. Accordingly,where the complementary surface does not conform to the contour of theseal 12, the seal interface may include one or more engagement portionsat each of the location where the seal 12 contacts the complementarysurface. Further, each of the seal engagement portions may include thesame or even different types of materials depending on the compositionand arrangement of the materials used to form the seal 12.

In the illustrated embodiment, the seal 12 includes the body 50 havingthe first elastomer portion 52 flanking the second elastomer portion 54.The body 50 includes the first elastomer portion 52 having a generallyrectangular shape (e.g., cross-sectional profile) and the nested secondelastomer portion 54. In one embodiment, nested refers to a set of itemsor parts forming a hierarchical structure with larger parts (e.g., thefirst elastomer portion 52) enclosing smaller ones (e.g., the secondelastomer portion 54). The second elastomer portion 54 includes an outersecond elastomer 66 adjacent (e.g., sharing a boundary with) the outerface 58 and an inner second elastomer 68 adjacent the inner face 56.Accordingly, each of the outer soft elastomer 66 and the inner softelastomer 68 include a band of material that is disposed in the outerand inner diameter of the first elastomer portion 52. In other words,the first elastomer portion 52 includes an “I” shaped cross-section withthe second elastomer portion 54 embedded into the outer face 58 and theinner face 56 of the body 50.

As will be appreciated, the shape of the first elastomer portion 52 andthe second elastomer portion 54 may be varied to accommodate specificapplications. For example, the first elastomer portion 52, in oneembodiment, includes a shape (e.g., cross-sectional profile) thatincludes chamfers or other features conducive to seating, setting andlocking the seal 12. Another embodiment includes only one of the secondelastomer portions 54. For example, an embodiment includes only theouter soft elastomer 66, and another embodiment includes only the secondsoft elastomer 68. Further, the shape and location of each of the firstand second sealing portions 52 and 54 may be varied. For instance, thesecond elastomer portions 54 may not be disposed symmetrically about thebody 50. In one embodiment, the outer soft elastomer 66 is offset fromthe inner soft elastomer 68 in a direction generally parallel to thelongitudinal axis 64. Further, the size and shape of each of the outersoft elastomer 66 and the inner soft elastomer 68 may be varied. Forexample, in one embodiment, the height and/or width of the outer portion66 is less than or greater than the height and/or width of the innerportion 68. Similarly, an embodiment may include varying the shapes ofthe soft elastomer portions 54. For example, in one embodiment, theouter soft elastomer 66 includes a generally rectangular shape (e.g., aprofile similar to those depicted) and the inner soft elastomer 68 has asemi-circular shape, or vice-versa. Further, embodiments include thefirst elastomer portion 52 and/or the second elastomer portion 54including indentations and protrusions (e.g., bumps) that extendradially from the faces 56 and 58 the seal 12. Embodiments including thevaried cross-sectional geometry of the seal 12 are discussed in furtherdetail below with regard to FIGS. 4-23.

The first elastomer portion 52 and the second elastomer portion 54include different materials that work cooperatively to provide thedesired fluid seal in a range of environments. In one embodiment, theseal 12 includes a first elastomer portion 52 formed from a hardelastomer that is resistant to corrosive attacks and conducive to use inhigh-temperature environments, and includes a second elastomer portion54 conducive to sealing in low-temperature environments. Thus, the seal12 may effectively seal over a broader range of temperatures andpressures as compared to a single elastomer seal. For example, at hightemperatures, the hard first elastomer portion 52 is conducive tosealing between the inner and outer faces 56 and 58 of the seal 12, andthe inner and outer bodies 14 and 16, respectively. Accordingly, inembodiments including the first elastomer portion 52 flanking (e.g.,surrounding) the second elastomer portion 54, as discussed with regardto FIG. 2, the first elastomer portion 52 effectively prevents corrosivefluids and/or high temperature and pressure fluids from engaging thesecond elastomer portion 54. At low temperatures (e.g., those below theeffective sealing temperature of the first elastomer portion 52), thesofter second elastomer portion 54 maintains the desired fluid sealbetween the inner and outer faces 56 and 58 of the seal 12, and theinner and outer bodies 14 and 16, respectively. For example, at lowtemperatures, the harder first elastomer portion 52 may not provide aneffective fluid seal and, thus, expose the softer second elastomerportion 54 to the environment, including the sealing temperatures,pressure and corrosive chemicals proximate to the seal 12. However, atreduced temperatures, the softer elastomer maintains itsleathery/rubbery state and conforms to the sealing surfaces (e.g., innerbody 14 and outer body 16). Further, it will be appreciated that atlower temperatures, the threat of corrosive (e.g., chemical) attack onelastomers is reduced, thus, making the soft elastomer suitable forsealing the corrosive low temperature environment. Accordingly, at lowtemperatures, the soft second elastomer portion 54 can provide thedesired fluid seal, and the hard first elastomer portion 52 can providethe fluid seal at higher temperatures.

The combination of the harder first elastomer portion 52 and the softersecond elastomer portion 54 may enable the seal 12 to maintain a fluidseal during rapid pressure fluctuations. For example, the seal 12 may beresistant to failures associated with explosive decompression. Explosivedecompression (ED) refers to a sudden marked drop in the pressure of asystem, associated with explosive violence. The pressure drop may occurover several minutes, and in an extreme case may occur in less than 0.1seconds. Generally ED results from some sort of material fatigue orengineering failure, causing a contained system to suddenly vent intothe external atmosphere. Seals 12 in high-pressure vessels (e.g.,mineral extraction systems 10) are susceptible to explosivedecompression. For example, a porous elastomer of the seals 12 canbecome saturated with high-pressure gases, and if the pressure insidethe vessel is suddenly released, then the gases within the elastomericseal 12 may expand violently, causing blistering or explosion of thematerial. Embodiments of the seal 12, including the first elastomerportion 52 flanking the second elastomer portion 54, help to prevent orreduce the effects of explosive decompression. In one embodiment, thefirst elastomer portion 52 effectively seals off the second elastomerportion 54 from the surrounding high pressure. In other words, the firstelastomer portion 52 does not fail due to ED and, thus, protects thesofter (e.g., porous) second elastomer portion 54 from the rapid drop inpressure associated with ED. The resistance from explosive decompressionfailure may be attributed to the lower permeability, and increasedfracture resistance of the hard elastomer with respect to service media.For example, the lower permeability of the hard elastomer prevents theelastomer from becoming saturated with a significant amount ofhigh-pressure gas. Accordingly, during ED, the first elastomer portion52 may isolate the second elastomer portion 54 from the rapid change inpressure. Further, even if the first elastomer portion 52 fails due toED, the second elastomer portion 54 may not have become saturated with ahigh-pressure gas due to the first elastomer portion 52 isolating thesecond elastomer portion 54 from high pressure over the period precedingED. Thus, decompression of the surrounding environment may not be fatalto the seal 12 because there is not a significant amount gas internal tothe second elastomer portion 54. In addition, the presence of the firstelastomer portion 52 may slow the sequence of decompression, preventingfailure of the seal 12 due to ED. In other words, if there is a failurein the first elastomer portion 52, the rate of the pressure dropexperienced by the second elastomer portion 54 may be reduced due to theadditional buffer provided by the first elastomer portion 52. Forexample, the strength, stiffness and resilience of the outer elastomerportion 52 may prevent a rapid pressure drop in the second elastomerportion 54.

The first and second elastomer portions 52 and 54 may be characterizedas hard and/or soft by a variety of metrics. In one embodiment, thehardness of the elastomers may be characterized by the resistance toindentation, otherwise referred to as the materials Durometer (D)denoted in the Shore A scale. In another embodiment, the elastomers maybe characterized as hard or soft based on their stiffness (e.g., glasstransitions temperature). However, despite the metric, the first andsecond elastomer portions 52 and 54 may simply have differentcharacteristics, properties, or responses to various conditions (e.g.,temperatures, pressure, corrosive materials, etc.) in a mineralextraction system.

In a characterization including the Durometer, materials are generallycharacterized based on ranges. Hard elastomers generally include thosehaving a Durometer greater than about 80 Shore A, soft elastomersgenerally include those having a Durometer of about 60 Shore A to about80 Shore A, and super-soft elastomers generally include those having aDurometer below about 60 Shore A. It will be appreciated that super-softelastomers are rarely used in oil-field and other mineral extractionsystems 10; however, the inclusion of a protective first elastomerportion 52 may enable these super-soft elastomers to be included in theseal 12.

In one embodiment of the seal 12, the first elastomer portion 52includes a hard elastomer having a Durometer of about 90 Shore A, andthe second elastomer portion 54 includes a soft elastomer portion 54having a Durometer of about 70 Shore A. For example, in one embodiment,the first elastomer portion 52 includes a hydrogenated nitrile butadienerubber (HNBR) having a Durometer of about 90 Shore A, and the secondelastomer portion 54 includes a nitrile rubber (NBR) having a Durometerof about 70 Shore A. Other embodiments may include various combinationsof hard, soft and super-soft materials. For example, one embodimentincludes two hard elastomers, wherein the second elastomer portion 54has a Durometer below the Durometer of the first elastomer portion 52.Another embodiment includes a hard or soft first elastomer portion 52and a super-soft second elastomer portion 54. As is discussed below withregard to FIGS. 4-23, the seal 12 may includes various combinations ofhard, soft and super-soft elastomers. Further, an embodiment may includethe first elastomer portion 52 and/or the second elastomer portion 54formed from a CAMLAST™ or a DUROCAM™ material manufactured by Cameronwith headquarters in Houston, Tex.

In a seal 12 including materials characterized by stiffness, the firstelastomer portion 52 may include an elastomer having a high stiffness ina particular (e.g., operating) temperature range and the secondelastomer portion 54 may include an elastomer having a relatively lowstiffness in the similar temperature range. Turing now to FIG. 3, a plot80 illustrates stiffness (e.g., elastic modulus stiffness (E)) versustemperature for two elastomers. The first curve 82 is indicative of thestiffness versus temperature plot for a relatively hard first elastomer,and the second curve 84 is indicative of the stiffness versustemperature plot for a relatively soft second elastomer. The first curve82 indicates the first elastomer having a first glass transitiontemperature (TG1) 86, and the second curve 84 is indicative of thesecond elastomer having a second glass transition temperature (TG2) 88that is below the first glass transition temperature (TG1) 86. The glasstransition temperature is the temperature below which the physicalproperties of amorphous materials vary in a manner similar to those of acrystalline phase (glassy state), and above which amorphous materialsbehave like liquids (rubbery/leathery state). Accordingly, the firstelastomer includes a glassy region 90 below the first glass transitiontemperature (TG1) 86 and the second elastomer includes a glassy region92 below the second glass transition temperature (TG2) 88. Further, theplot 80 includes a region 96 that is above the glass transitiontemperature (e.g., TG1) of both elastomers. Thus, in the temperatureregion 92 both elastomers may include a glassy state. When theelastomers are in a temperature region 94, the first elastomer mayinclude glassy state, and the second elastomer may include an amorphous(e.g., rubbery/leathery) state. Finally, in the temperature region 96,both elastomers may include an amorphous state.

The inclusion of at least a first elastomer (e.g., 82) and a secondelastomer (e.g., 84) enables the seal 12 to operate effectively over awider range of temperatures, pressures, and other environmentalconditions. For example, in a seal 12 including only the firstelastomer, the seal 12 may be ineffective at about or below the firstglass transition temperature TG1 (86). In other words, at or below thefirst glass transition temperature (TG1 (86)), the first elastomer maytransition to a glassy state, and seal 12 is unable to conform to thesealing surfaces (e.g., the hanger 24 and the wellhead bore 26). Forinstance, the first elastomer may shrink, retract, and/or embrittle dueto the low temperatures, until it is unable to seal against acomplementary surface. However, the inclusion of the second elastomer(e.g., 84) may provide for sealing at or below the first glasstransition temperature (TG1 (86)). For example, at a temperature in theregion 94 (e.g., between TG1 (86) and TG2 (88)) the first elastomer maytransition into glassy state enabling fluids to pass, and the secondelastomer remains in an amorphous state conducive to sealing. In otherwords, the inclusion of the second elastomer widens the operatingtemperature range of the seal 12 to include temperatures in the region94. For example, in one embodiment, the difference between the firstglass transition temperature (TG1) 86 and the second glass transitiontemperature (TG2) 88 is approximately 10 degrees Fahrenheit (° F.).Accordingly, the seal 12 may be rated for use in environmentalconditions that are ten degrees Fahrenheit below that of a sealincorporating only the first elastomer. For example, in one embodimentthe glass transition temperature of the first elastomer may beapproximately 0° F. and the glass transition temperature of the secondelastomer may be approximately −40° F., thus expanding the effectiveoperating range of the seal 12 by approximately 40° F.

As will be appreciated, the potential for chemical attack on anelastomer increases as the temperature increases. Further, softermaterials are generally more susceptible to chemical attack and maydegrade or loose physical properties at lower temperature thanrelatively hard elastomers. Thus, similar to the second elastomerextending the lower operating range of the seal 12, the first elastomerextends the upper operating range of the seal 12. In other words, wherethe second elastomer is heated to a temperature that causes it to faildue to a chemical attack, or the elastomer transitions from aleathery/rubbery amorphous state to a degraded state, the firstelastomer continues to provide an effective fluid seal. Accordingly, asdiscussed above, the seal 12 in certain embodiments enables the firstelastomer to protect the second elastomer at elevated operatingtemperatures. For example, in an embodiment where the first elastomerflanks the second elastomer, the first elastomer isolates the secondelastomer from the chemical attack and/or the elevated temperatures andpressures proximate to the seal 12.

An exemplary embodiment of the seal 12 includes a first elastomerportion 52 including high-temperature, 90 Shore A Durometer FKM (e.g., atype of fluorinated elastomer) and the second elastomer includinglow-temperature, 90 Shore A Durometer FKM. The first elastomer portion52 formed from high-temperature, 90 Shore A Durometer FKM includes anoperating range of approximately 35° F. to 350° F., and the secondelastomer portion 54 formed from low-temperature, 90 Shore A DurometerFKM includes an operating range of approximately −50° F. to 250° F.Accordingly, the seal 12 includes an operating temperature range ofapproximately −50° F. to 350° F. Further, the seal 12 may effectivelyseal pressures up to and exceeding approximately 20,000 pounds persquare inch (PSI). Other embodiments include various elastomers andcombinations of elastomers to effectively increase or decrease theoperating range of the seal 12.

Forming the seal 12 may include a variety of process to effectivelyinterface the elastomer portions 52 and 54. In one embodiment, each ofthe elastomer portions 52 and 54 are extrusion molded separately and,subsequently compression molded together to provide the body 50.Accordingly, the body 50 includes a homogeneous structure that includesan interface between the elastomer portions that does not includeauxiliary shear stresses (e.g., friction) between the portions. In otherwords, there is no boundary layer between the two materials. Anotherembodiment includes vulcanizing the first elastomer portion 52 and thesecond elastomer portion 54 to one another. For instance, in oneembodiment, after each of the elastomer portions 52 and 54 are formed,they are cured in a vulcanization process. Curing the seal 12 in thevulcanization process includes exposing the elastomer portions 52 and 54to high temperature, high pressure, and catalysts (e.g., sulfur) tocross-link the molecules of the elastomers 52 and 54. As a result, theseal 12 forms a homogeneous body 50 more resistant to chemical attack.Other embodiments of forming the seal 12 include a variety of processes.For example, one embodiment includes the use an adhesive to adhere theelastomer portions 52 and 54 to one another. Further, certainembodiments include machining the elastomers to the desired shape beforeor after coupling the elastomers to one another. In addition, the abovediscussed processes may be employed to couple (e.g., vulcanize) aplurality of elastomers to one another to form the seal 12. For example,2, 3, 4, 5, 6, 7, 8, 9, 10, or more different elastomers may bevulcanized to form the seal 12 with an increased operating range.

In addition to the embodiments of seal 12 discussed with regard to thecross-section illustrated in FIG. 2, other embodiments include alternateconfigurations and geometries of the elastomer portions 52 and 54including similar materials and forming techniques. For example, certainembodiments include more than two elastomer portions integral to theseal 12. Further, embodiments include T-seals, S-seals, Metal-End-Capseals, face seals, and the like.

Turning now to FIG. 4, an embodiment of the seal 12 including a firstelastomer portion 52 and second elastomer portion 54 extending throughthe body 50, is illustrated. The second elastomer portion 54 includes asingle layer disposed directly between and separating a first elastomertop layer 100 and a first elastomer bottom layer 102. The secondelastomer portion 54 extends adjacent to the inner surface 56 and theouter surface 58 of the seal 12. In other words, the second elastomerportion 54 includes a layer of elastomer that is sandwiched between thefirst elastomer portions 52. “Sandwiched” refers to the disposition ofthe first elastomer portion 52 about at least two sides of the secondelastomer portion 52. In one embodiment, the first elastomer portions 52include a hard elastomer, and the second elastomer portion 54 includes asoft elastomer. In other embodiments, each portion of the seal 12includes a different material and/or properties, e.g., differinghardness/stiffness/Durometer. For example, in one embodiment, the firstelastomer top portion 100 includes a hard elastomer, the secondelastomer portion 54 includes a soft elastomer, and the first elastomerbottom portion 102 includes a super-soft elastomer.

FIG. 5 illustrates an embodiment of the seal 12 including a plurality ofelastomer layers in the body 50 of the seal 12. In the illustratedembodiment, the seal 12 includes a third elastomer portion 104, thesecond elastomer portion 54 and the first elastomer portion 52. Thethird elastomer portion 104 includes a single layer, the secondelastomer portion 54 includes a second elastomer top layer 106 and asecond elastomer bottom layer 108 disposed about the third elastomerportion 104, and the first elastomer portion 52 includes the firstelastomer top layer 100 and the first elastomer bottom layer 102disposed about the second elastomer portion 54. Each of the firstelastomer portion 52, the second elastomer portion 54 and the thirdelastomer portion 104 extends adjacent to the inner surface 56 and theouter surface 58 of the seal 12. In other words, the seal 12 includes aplurality of elastomer layers sandwiched between outer elastomer layers.

FIG. 6 illustrates an embodiment of the seal 12 including a plurality ofelastomer portions nested in the body 50 of the seal 12. In theillustrated embodiment, the seal 12 includes the first elastomer portion52, the second elastomer portion 54 and the third elastomer portion 104.The first elastomer portion 52 includes a rectangular body similar tothat discussed with regard to FIG. 2. Further, the second elastomerportion 54 includes the inner and outer second elastomer portions 68 and66 similar to those discussed with regard to FIG. 2. The third elastomerportion 104 includes an inner third elastomer 106 and an outer elastomerportion 108. As illustrated, the inner third elastomer 106 isimmediately surrounded by the inner second elastomer portion 68, and theouter third elastomer portion 108 is immediately surrounded by the outersecond elastomer portion 66. Further, the inner third elastomer 106includes a face adjacent the inner face 56 of the seal 12, and the outerthird elastomer 108 includes a face adjacent the outer face 58 of theseal 12. In other words, the body 50 of the seal 12 includes the firstelastomer portion 52, a plurality of bands of the second elastomerportion 54 nested in the inner and outer diameter of the first elastomerportion 52, and a plurality of bands of the third elastomer portion 104nested in each of the second elastomer portions 54. In one embodiment,the seal 12 includes only one of the inner second and third elastomerportions 68 and 106 or the outer second and third elastomer portions 66and 108. Further, other embodiments may include any combination of thefirst, second and third elastomer portions 52, 54, 104.

FIG. 7 illustrates an embodiment of the seal 12 including a plurality ofelastomer portions offset and integral to the body 50 of the seal 12. Inthe illustrated embodiment, the seal 12 includes the first elastomerportion 52, the second elastomer portion 54, the third elastomer portion104 and a fourth elastomer portion 110. Each of the second, third andfourth elastomer portions 54, 104, 110 are disposed in series along theface of the faces 56 and 58 of the seal 12. For example, the secondelastomer portion 52 includes the inner and outer second elastomer 68and 66, the third elastomer portion 104 includes the inner and outerthird elastomers 106 and 108, and the fourth elastomer portion 110includes an inner fourth elastomer 112 adjacent the inner face 56 of theseal 12, and an outer fourth elastomer 114 adjacent the outer face 58 ofthe seal 12. Accordingly, each of the second, third and fourthelastomers include separate rings disposed proximate to one another inthe inner and outer diameters of the seal 12. In one embodiment, thesecond and fourth elastomer portions 54 and 110 include the same type ofelastomer. For example, in one embodiment, the first elastomer portion52 includes a hard elastomer, the second and fourth elastomer portions54 and 110 include a soft elastomer, and the third elastomer portion 104includes a super-soft elastomer.

As mentioned previously, embodiments of the seal 12 include employingsimilar techniques in various types of seals 12. FIG. 8 illustrates anS-seal in accordance with embodiments of the present technique. The seal12 includes the body 50 having a protrusion 120 in the outer diameter(OD), and integral anti-extrusion springs 122. Similar to theembodiments described with regard to FIG. 2, the seal 12 includes thefirst elastomer portion 52 flanking the second elastomer portion 54. Forexample, the body 50 includes the first elastomer portion 52 having agenerally rectangular shape (e.g., cross-sectional profile), includingthe protrusion 120 extending from the outer diameter of the seal 12, andthe nested second elastomer portion 54. The second elastomer portion 54includes the outer second elastomer 66 adjacent (e.g., sharing aboundary with) the outer face 58 and the inner second elastomer 68adjacent the inner face 56. For example, each of the outer secondelastomer 66 and the inner second elastomer 68 includes a band ofmaterial that is disposed in the outer and inner diameters of the firstelastomer portion 52. As will be appreciated, similar to the discussionregarding FIG. 2, the cross-section of the first elastomer portion 52and the second elastomer portion 54 may be varied to accommodatespecific applications. For example, FIG. 9 illustrates the seal 12including an S-seal having the protrusion 120 and the anti-extrusionsprings 122 disposed on the internal diameter of the seal 12.

Further, embodiments including an S-seal 12 may incorporate any of thefeatures discussed with regard to FIGS. 4-7. For example, similar to theembodiment illustrated and discussed with regard to FIG. 4, FIG. 10illustrates an S-seal including a layer of the second elastomer 54extending between the inner face 56 and the outer face 58. In theillustrated embodiment, the second elastomer portion 54 includes asingle layer disposed directly between and separating the firstelastomer top layer 100 and the first elastomer bottom layer 102,wherein the second elastomer portion 54 extends adjacent to the innersurface 56 and the outer surface 58 of the seal 12. Further, theembodiment includes the protrusion 120 in the outer diameter (OD), andintegral anti-extrusion springs 122. Other embodiments include across-section of the seal 12 including multiple elastomer layers (seeFIG. 5), multiple elastomer layers (see FIG. 6), multiple elastomersoffset and integral to the body 50 (see FIG. 7), and the like.

FIG. 11 illustrates a T-seal in accordance with embodiments of thepresent technique. The seal 12 includes a protrusion 130 in the outerdiameter (OD), and extrusion rings 132 disposed integral to theprotrusion 130. The extrusion rings 132 may include PEEK(polyetheretherketone), metal, or other hard plastic materials, forinstance. Similar to the embodiments described with regard to FIGS. 2and 8, the seal 12 includes the first elastomer portion 52 flanking thesecond elastomer portion 54. For example, the body 50 includes the firstelastomer portion 52 having a generally rectangular shape (e.g.,cross-sectional profile) including the protrusion 130 extending from theouter diameter of the seal 12 and the integral second elastomer portion54. The second elastomer portion 54 includes the outer second elastomer66 adjacent (e.g., sharing a boundary with) the outer face 58 and theinner second elastomer 68 adjacent the inner face 56. For example, eachof the outer second elastomer 66 and the inner second elastomer 68includes a band of material that is disposed in the outer and innerdiameters of the first elastomer portion 52. As will be appreciated,similar to the discussion regarding FIGS. 2 and 8, the cross-section ofthe first elastomer portion 52 and the second elastomer portion 54 canbe varied to accommodate specific applications. For example, FIG. 12illustrates the seal 12 including a T-seal having the protrusion 130 andthe extrusion rings 122 disposed on the internal diameter of the seal12.

Further, embodiments of the T-seal 12 may incorporate any of thefeatures discussed with regard to FIGS. 4-7. For example, similar to theembodiment illustrated and discussed with regard to FIGS. 4 and 10, FIG.13 illustrates a T-seal including a layer of the second elastomer 54extending between the inner face 56 and the outer face 58. In theillustrated embodiment, the second elastomer portion 54 includes asingle layer disposed directly between and separating the firstelastomer top layer 100 and the first elastomer bottom layer 102,wherein the second elastomer portion 54 extends adjacent to the innersurface 56 and the outer surface 58 of the seal 12. Further, theembodiment includes the protrusion 130 in the outer diameter (OD), andextrusion rings 132. Other embodiments may include a cross-section ofthe seal 12 including multiple elastomer layers (see FIG. 5), multipleelastomer layers (see FIG. 6), multiple elastomers offset and integralto the body 50 (see FIG. 7), and the like.

FIG. 14 illustrates a Metal-End-Cap seal in accordance with embodimentsof the present technique. The seal 12 includes metal caps 140 disposedon the top and bottom faces 60 and 62 of the seal 12. Further, the seal12 includes a cross-section having chamfers 142 defining a firstprotrusion 144 including the outer face 58. The internal diameterincludes a second protrusion 146 that defines the inner face 56. Similarto the embodiments described with regard to FIGS. 2, 8 and 11, the seal12 includes the first elastomer portion 52 flanking the second elastomerportion 54. For example, the body 50 includes the first elastomerportion 52 having a generally rectangular shape (e.g., cross-sectionalprofile) including the protrusions 144 and 146 and the nested secondelastomer portion 54. The second elastomer portion 54 includes the outersecond elastomer 66 integral to the first protrusion 144 and adjacent(e.g., sharing a boundary with) the outer face 58, and the inner secondelastomer 68 integral to the second protrusion 146 and adjacent theinner face 56. For example, each of the outer second elastomer 66 andthe inner second elastomer 68 includes a band of material that isdisposed in the outer and inner diameters of the first elastomer portion52. As will be appreciated, similar to the discussion regarding FIGS. 2,8 and 11, the cross-section of the first elastomer portion 52 and thesecond elastomer portion 54 may be varied to accommodate specificapplications.

FIG. 15 illustrates the Metal-End-Cap seal 12 having the firstprotrusion 144 and the chamfers 142 disposed on the internal diameter ofthe seal 12. Further, the shape and location of each of the first andsecond sealing portions 52 and 54 may be varied. For instance, thesecond elastomer portions 54 may not be disposed symmetrically about thebody 50. In one embodiment, the outer second elastomer 66 is offset fromthe inner second elastomer 68 in a direction generally parallel to thelongitudinal axis 64. Further, the size and shape of each of the outersecond elastomer 66 and the inner second elastomer 68 may be varied. Forexample, FIG. 16 illustrates an embodiment of the Metal-End-Cap seal 12,wherein the height 148 and width 150 of the inner second elastomer 68 isgreater than the height 152 and width 154 of the outer second elastomer66.

Further, the Metal-End-Cap seal 12 may incorporate any of theembodiments of the seal 12 discussed with regard to FIGS. 4-7. Forexample, similar to the embodiments illustrated and discussed withregard to FIGS. 4, 10 and 13, FIG. 17 illustrates the Metal-End-Cap seal12 including a layer of the second elastomer 54 extending between theinner face 56 and the outer face 58. In the illustrated embodiment, thesecond elastomer portion 54 includes a single layer disposed directlybetween and separating the first elastomer top layer 100 and the firstelastomer bottom layer 102, wherein the second elastomer portion 54extends adjacent to the inner surface 56 and the outer surface 58 of theseal 12.

Other embodiments include a cross-section of the seal 12 includingmultiple elastomer layers. For example, similar to the embodiment of theseal illustrated in FIG. 5, FIG. 18 illustrates an embodiment of theMetal-End-Cap seal 12 including a plurality of elastomer layers in thebody 50 of the seal 12. In the illustrated embodiment, the seal 12includes the third elastomer portion 104, the second elastomer portion54 and the first elastomer portion 52. The third elastomer portion 104includes a single layer, the second elastomer portion 54 includes thesecond elastomer top layer 106 and the second elastomer bottom layer 108disposed about the third elastomer portion 104, and the first elastomerportion 52 includes the first elastomer top layer 100 and the firstelastomer bottom layer 102 disposed about the second elastomer portion54. Each of the first elastomer portion 52, the second elastomer portion54 and the third elastomer portion 104 extends adjacent to the innersurface 56 and the outer surface 58 of the seal 12. In other words, theseal 12 includes a plurality of elastomer layers sandwiched betweenouter elastomer layers.

FIG. 19 illustrates an embodiment of the Metal-End-Cap seal 12 includingmultiple nested elastomer layers similar to the embodiment of thecross-section illustrated in FIG. 6. In the illustrated embodiment, theseal 12 includes the first elastomer portion 52, the second elastomerportion 54 and the third elastomer portion 104. The first elastomerportion 52 includes the rectangular body 50, and the second elastomerportion 54 includes the inner and outer second elastomer portions 66 and68. The third elastomer portion 104 includes the inner third elastomer106 and the outer elastomer portion 108. As illustrated, the inner thirdelastomer 106 is immediately surrounded by the inner second elastomerportion 68, and the outer third elastomer portion 108 is immediatelysurrounded by the outer second elastomer portion 66. Further, the innerthird elastomer 106 includes a face adjacent the inner face 56 of theseal 12, and the outer third elastomer portion 108 includes a faceadjacent the outer face 58 of the seal 12. Another embodiment of theMetal-End-Cap seal 12 may includes multiple elastomers offset andintegral to the body 50 (see FIG. 7), and the like.

In addition, to the previously discussed features, the seal 12 mayincorporate additional features to improve the seal. For example,embodiments of the seal 12 include a cross-section including a pluralityof indentations. Indentations in the cross-section translate intogrooves that extend about the internal and external diameter of the seal(e.g., faces 56 and 58). The grooves effectively create ridges thatprovide areas of increased contact stress to maintain a fluid sealbetween the seal 12 and the internal and external bodies 14 and 16. Forinstance, FIG. 20 illustrates an embodiment of the seal 12 including aplurality of indentations 160. The indentations include inner diameterindentations 162 and outer diameter indentation 164. Further, theindentations 160 are disposed in a plurality of the elastomers. Forinstance, the indentations 160 may include annular grooves in the firstelastomer portion 52 and the second elastomer portion 54. In theillustrated embodiment of FIG. 20, the inner and outer indentations 162and 162 are generally symmetrical about an axis 160 running down thecenter of the cross-section of the seal 12. In other words, thegeometries of the indentations 160 are identical on the inner face 56and the outer face 58.

Other embodiments of the seal 12 include asymmetrical profiles on theinternal diameter and the external diameter of the seal 12. FIG. 21illustrates an embodiment including a Metal-End-Cap seal 12 having anasymmetrical profile on the inner face 56 and the outer face 58. Forexample, the illustrated embodiment includes two indentations 162 on theinner face 56 of the seal 12, and a single indentation 164 on the outerface 58 of the seal 12. In other words, the seal 12 cross-sectionincludes a first geometry on the internal diameter and a second geometryon the external diameter that is different from the first geometry.Similar features may be incorporated into a variety of seals. Forexample, embodiments include the asymmetric or symmetric profileemployed in a T-seal, an S-seal, and the like.

Although the above discussion focuses primarily on annular (e.g.,radial) seals 12, similar techniques may be employed in the design anduse of face seals. Face seals generally include seals 12 that provide afluid seal between two generally flat surfaces. For example, FIG. 22illustrates an embodiment of a face seal 12 in accordance withtechniques of the present technique. The seal 12 includes the body 50,the first elastomer portion 52, the second elastomer portion 54, theinner face 56, the outer face 58, the top face 60 and the bottom face62. In operation, the top face 60 is mated to a first body and thebottom face 62 is mated to a second body to provide a fluid seal betweenthe first and second bodies. Accordingly, embodiments include theaddition of sealing features conducive to sealing via the top and bottomfaces 60 and 62. For example, as illustrated in FIG. 22, the secondelastomer portion 54 includes a top second elastomer 170 adjacent thetop face 60 and a bottom second elastomer 172 adjacent bottom face 62.Thus, the first elastomer portion 52 flanks the second elastomer portion54 in a similar manner to that discussed with regard to FIG. 2.

In another embodiment, the second elastomer portion includes a singlelayer passing through the cross-section of the seal 12. For example,FIG. 23 includes an embodiment similar to those illustrated anddiscussed with regard to FIGS. 4, 10, 13 and 17. As illustrated in FIG.23, the seal 12 includes a first elastomer portion 52, and a secondelastomer portion 54. The second elastomer portion 54 includes a singlelayer disposed between a first elastomer inner layer 176 and a firstelastomer outer layer 178. The second elastomer portion 54 extendsadjacent to the top face 60 and the bottom face 62 of the seal 12. Otherembodiments include the face seal 12 having cross-sections similar tothose discussed with regard to FIGS. 4-21.

Each of the above discussed embodiments of the seal 12 may include anycombination of elastomers and cross-sections conducive to providing afluid seal. For example, each separate portion may include an elastomerhaving a different hardness, stiffness or glass transition temperature.Further, embodiments may include combinations of the embodiedcross-sections. For example, an embodiment includes a cross-sectionincluding a profile similar to FIG. 2 at the inner face 56, and across-section including a profile similar to FIG. 6 on the outer face58.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

1-32. (canceled)
 33. A system, comprising: a fluid seal, comprising: afirst seal interface extending circumferentially about a central axis ofthe fluid seal; a second seal interface extending circumferentiallyabout the central axis of the fluid seal, wherein the first and secondseal interfaces face radially away from one another relative to thecentral axis; a body elastomer portion extending circumferentially alongthe first and second seal interfaces; and a first elastomer portionextending circumferentially along the first seal interface, wherein thefirst elastomer portion is recessed within the body elastomer portion;and a second elastomer portion extending circumferentially along thesecond seal interface, wherein the second elastomer portion is recessedwithin the body elastomer portion, wherein the body, first, and secondelastomer portions are vulcanized together.
 34. The system of claim 33,wherein the body elastomer portion is effective to seal at a temperatureabove an effective sealing temperature of the first and second elastomerportions.
 35. The system of claim 33, wherein the body elastomer portionhas a glass transition temperature that is greater than the first andsecond elastomer portions.
 36. The system of claim 35, wherein the glasstransition temperature of the body elastomer portion is at least 10degrees greater than the first and second elastomer portions.
 37. Thesystem of claim 33, wherein the body elastomer portion comprises a hardelastomer and the first and second elastomer portions comprises a softelastomer.
 38. The system of claim 33, wherein the body elastomerportion comprises hydrogenated nitrile butadiene rubber (HNBR) and thefirst and second elastomer portions comprises nitrile rubber (NBR). 39.The system of claim 33, wherein the body elastomer portion comprises afirst hardness of greater than about 90 Shore A Durometer, and the firstand second elastomer portions comprises a second hardness of less thanabout 80 Shore A Durometer.
 40. The system of claim 33, wherein the bodyelastomer portion has a greater resistance to chemical attack than thefirst and second elastomer portions.
 41. The system of claim 33,comprising a first metal end cap disposed on a first axial end of thefluid seal, and a second metal end cap disposed on a second axial end ofthe fluid seal.
 42. The system of claim 33, wherein the body, first, andsecond elastomer portions are annular, wherein the body elastomerportion extends about opposite axial sides of both the first and secondelastomer portions.
 43. The system of claim 42, comprising a firstplurality of protrusions or indentions extending along the first sealinterface, and a second plurality of protrusions or indentions extendingalong the second seal interface.
 44. The system of claim 33, wherein thefluid seal is effective to seal up to at least 15,000 pounds per squareinch of fluid pressure.
 45. The system of claim 33, wherein the fluidseal is effective to seal up to at least 20,000 pounds per square inchof fluid pressure.
 46. The system of claim 33, comprising at least onecomponent of a mineral extraction system having the fluid seal.
 47. Asystem, comprising: a fluid seal, comprising: a first seal interfaceextending circumferentially about a central axis of the fluid seal; abody elastomer portion extending circumferentially along the first sealinterface; and a first elastomer portion extending circumferentiallyalong the first seal interface, wherein the first elastomer portion isrecessed within the body elastomer portion, and the body and firstelastomer portions are vulcanized together.
 48. The system of claim 47,wherein the body elastomer portion has a greater effective sealingtemperature, a greater chemical resistance, a greater hardness, or anycombination thereof, relative to the first elastomer portion.
 49. Thesystem of claim 47, wherein the body elastomer portion has a glasstransition temperature that is greater than the first elastomer portion,the body elastomer portion comprises a hard elastomer and the firstelastomer portion comprises a soft elastomer, and the fluid seal iseffective to seal up to at least 15,000 pounds per square inch of fluidpressure.
 50. The system of claim 47, comprising a first metal end capdisposed on a first axial end of the fluid seal, and a second metal endcap disposed on a second axial end of the fluid seal.
 51. The system ofclaim 47, wherein the body and first elastomer portions are annular, thebody elastomer portion extends about opposite axial sides of the firstelastomer portion, and a first plurality of protrusions or indentionsextend along the first seal interface.
 52. A system, comprising: a fluidseal, comprising: a first seal interface; a body elastomer portionextending along the first seal interface; and a first elastomer portionextending along the first seal interface, wherein the first elastomerportion is recessed within the body elastomer portion, and the body andfirst elastomer portions are vulcanized together.